Specifying Performance Requirements

Controlling the movement of air and heat through windows.
Patrick Roach
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Full Name: Patrick M. Roach AIA
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Specifying Performance Requirements

Postby Patrick Roach » August 16th, 2011, 11:31 am

Energy performance is a significant aspect of what drives this project. Having a performance standard for rehabilitated historic windows will not only provide a standard for judging the success of a project, but also can be a selling point when an owner makes a decision whether to save their historic windows or replace them.

We can take a page from the window manufacturing industry. AAMA/WDMA/CSA 101/IS2/A440 is a nationally-recognized performance standard which evaluates new windows based on several factors, including structural performance, air infiltration, water infiltration, break-in resistance, and thermal performance. Most categories are measured against a design performance factor, which is based on the anticipated wind pressure in pounds per square foot on the window's surface. The minimum performance standards listed are pretty soft in some areas. We usually ask for additional performance in certain areas over and above the standard design performance level. Most manufacturers can produce windows which beat these standards.

The AAMA/WDMA/CSA standard is not applicable to evaluation of existing windows, but the basic performance criteria and categories can help to define the key areas where these Standards can offer assurance that the finished product will perform in an acceptable fashion. It seems that the Standards should set forth minimum performance requirements based on air infiltration (with the Pine Mountain tests we are on our way to having data to establish this), water infiltration, and thermal transmittance (u-value). Window manufacturers establish their performance grade by testing sample products in the lab every few years. For historic windows, it seems that the performance data can be established by testing on installed conditions, similar to how it was done at Pine Mountain. The test data can serve not only to help sell window restoration, but also to determine appropriate treatments, and if necessary, to provide the performance criteria for a testing and inspection regimen on an individual project.

Having a demonstrated "service record" for these treatments, and established grounds for performance expectations, will go a long way in helping the case for window restoration.

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Re: Specifying Performance Requirements

Postby sschoberg » March 16th, 2012, 7:52 am

I hope performance standards are not the single most important thing driving this project. There are lots of reasons original windows should be maintained, repaired and restored over replacing them with a substandard low life replacement window. The main thing being that original windows will last forever, can be upgraded with weather stripping to compare with new replacement low life windows. (compare with and not neccesarily beat)

I think testing and weather stripping recommendations should be done as a study by WPSC and not in the main body of these standards. From a study such as performance specification, recommendation can be made and comparisons to more than one scenario and even comparison to more than one low life sub standard replacement window.

If these standards' main thrust is to go head to head to meat or beat performance standards of ne windows, the quality control thrust of this industry will lose. Quality restoration standards is what I though was the main thrust of this collaboration.

Again, I think the performance standards recommendations should be seperated from the main body of the the real purpose of the standards.

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Full Name: John Leeke
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Re: Specifying Performance Requirements

Postby johnleeke » March 16th, 2012, 10:26 am

Steve, you are right on the mark.

This project is mainly about setting standards on methods and materials.

Another part of the project is laying the groundwork for determining how these methods and materials perform. There are two categories of performance: durability and energy.

Durability, how long with the various methods and materials last.

Energy, what is the energy use and performance of the various methods and materials.

In this first edition of the Standards, we will not be setting any performance standards. That could be a part of the Window Standards project in future years, which is why we are considering and beginning to deal with performance issues now.
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